The invention relates to a method for adjusting the play between brake linings and a brake disc of a preferably pneumatically actuated disc brake by the use of at least one or more electromotively driven adjusting devices.
Fields of application of the invention are, on the one hand, the adjustment of electrically driven adjusting devices of pneumatically or hydraulically driven disc brakes, and on the other hand, the adjustment of disc brakes in which not only the adjustment, but also the application, takes place electromotively.
The invention is very particularly preferable for use in disc brakes having a pneumatically actuated brake application device or with a pneumatic force generating device, which acts on the brake application device, with the adjustment of the disc brake taking place electromotively. It is possible, here, to arrange one or more electromotively operated adjusting devices at one, or preferably both, sides of the brake disc.
It is known from the prior art, in the adjustment of electromotively driven wear adjusting systems, to firstly measure the “play” or “air play” in each case in an ongoing fashion, for example by use of a sensor, and to subsequently carry out a correction or adjustment. In this respect, reference is, for example, made to prior art reference EP 0 995 923 A2.
A disadvantage of this known prior art is the expenditure for the measurement of the parameters and the susceptibility to failure of the force sensors and travel or rotational angle sensors which act in the braking mechanism.
It is also disadvantageous that an air play measuring process can only take place in conjunction with a brake actuation.
It is, therefore, intended to provide a method, which avoids these disadvantages, for adjusting an air play of a disc brake by use of electromotively driven adjusting devices.
Here, the adjustment of the air play should take place without additional sensors, and it should nevertheless be possible to set the smallest possible air play, wherein the disadvantage of constantly repeatedly placing the brake linings in grinding contact with the brake disc also need not be accepted or need only be accepted to a small extent.
The invention meets these needs by providing a method for adjusting the air play between brake linings and a brake disc of a preferably pneumatically actuated disc brake by use of at least one or more electromotively driven adjusting devices. By use of a processor, changes in the air play as a result of braking operations are determined without sensors via a mathematical prognosis, wherein the wear occurring during the braking operation, and the time-based change of the components of the brake as a result of the energy released during braking operations, is incorporated in the prognosis. The changes determined in this way are corrected at predefined time intervals by way of corresponding adjusting processes by the at least one or more adjusting devices.
The invention thereby provides a method for adjusting the air play between brake linings on both sides of a brake disc of a disc brake by use of at least one electromotively driven adjusting device, in which method, by use of a processor—for example on the brake—changes in the air play as a result of braking operations are determined using a mathematical prognosis or simulation, wherein the change of the components of the brake as a result of the energy released during braking operations is incorporated in the prognosis, and the changes determined in this way are corrected at predefined “small” time intervals of, for example, a few seconds (for example 2 to 60 seconds) by way of corresponding adjusting processes.
It is the case in particular that, after a braking operation, the initially occurring expansion of the brake components, and then the contraction behavior of said components as a result of the subsequent cooling, is incorporated in the prognosis, and in that the one-off prognosis after a braking operation is used to carry out a plurality of successive adjusting processes after the braking operation.
It is expedient if at least the brake linings and the brake disc are incorporated in the calculation of the brake components, which expand and subsequently contract during the braking operation.
It is advantageously additionally the case that, at time intervals which are to be selected by way of the prognosis to be larger than the time interval of the adjusting processes, for example in each case after a few minutes or for example half an hour, a resetting of the air play is carried out by placing the brake linings in grinding contact against the brake disc with the adjusting devices and by a subsequent resetting to the nominal air play. In this way, during a relatively long journey, the air play is continuously set to the correct value by placing the brake linings against the disc, and possible deviations of the simulation from the actual conditions are corrected. This method step is carried out between braking operations with a sufficiently long time interval if sufficient time is available for carrying out the adjustment. If the adjustment is, for example, interrupted by a new braking operation, then the air play adjustment on the basis of the simulation is resorted to again in the first instance.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.